By Jessica I. Marschall, CPA, ISA AM
March 16th, 2025
The distinction between a business and a hobby under IRS rules can have profound financial implications. Many taxpayers assume that if they operate an activity with revenue, they qualify as a business. However, the IRS has the authority to retroactively reclassify an activity as a hobby, leading to the disallowance of prior-year deductions, interest accrual, and substantial underpayment penalties.
This article explores how the IRS determines whether an activity is a business or a hobby, the financial risks of reclassification, and the penalties taxpayers face when the IRS retroactively adjusts their tax filings.
Business vs. Hobby: The IRS’s Retroactive Authority
Under Internal Revenue Code (IRC) § 183, also known as the hobby loss rule, the IRS limits deductions for activities not engaged in for profit. If the IRS determines that an activity was not conducted with the intent to generate a profit, it can retroactively reclassify that income as hobby income, disallow business deductions, and impose penalties and interest.
Key IRS Factors in Determining Hobby vs. Business (Nine-Factor Test)
The IRS uses the following nine factors to determine whether an activity is a business or a hobby (Treas. Reg. § 1.183-2(b)):
- Manner in Which the Activity Is Conducted – Is the activity carried out in a businesslike manner with records, financial tracking, and a clear effort to improve profitability?
- Expertise of the Taxpayer and Advisors – Has the taxpayer sought expert advice to improve the activity’s profitability?
- Time and Effort Devoted to the Activity – Does the taxpayer devote significant time, or is it more of a passive endeavor?
- Expectation That Assets Used in the Activity May Appreciate – Even if the activity is unprofitable, are there reasonable expectations that assets (e.g., real estate, intellectual property) will gain value?
- Success in Carrying on Similar Activities – Has the taxpayer previously operated successful businesses?
- History of Income or Losses – Does the activity generate consistent losses over the years?
- Amount of Occasional Profits – Are profits occasional, minimal, or significantly less than expenses?
- Financial Status of the Taxpayer – Is the taxpayer relying on this activity for livelihood, or does it appear to be a recreational endeavor?
- Elements of Personal Pleasure or Recreation – Does the taxpayer derive substantial personal enjoyment from the activity, beyond any potential profit motive?
If an activity shows multiple years of losses and lacks business-like characteristics, the IRS may retroactively disallow deductions, converting previously claimed business expenses into non-deductible hobby losses.
The Financial Impact of IRS Reclassification
When the IRS retroactively recategorizes a business as a hobby, the taxpayer faces significant financial consequences, including:
1. Loss of Business Deductions (IRC § 183(a))
- Businesses can deduct ordinary and necessary expenses under IRC § 162.
- Hobbies can only deduct expenses up to income, under IRC § 183(b)(2)—meaning no net losses can offset other income.
Example:
- Taxpayer’s Original Filing: Reported a $50,000 business loss, offsetting W-2 income, reducing taxable income, and creating a refund.
- IRS Adjustment: The IRS reclassifies the activity as a hobby, disallows the $50,000 loss, and retroactively increases taxable income by $50,000.
Result:
- Taxpayer owes back taxes on $50,000 of now-taxable income.
- The IRS assesses interest and substantial penalties.
2. Interest on Underpaid Taxes (IRC § 6601)
- When taxes are underpaid due to a retroactive IRS adjustment, the taxpayer owes interest from the original due date until full payment.
- The current IRS interest rate (as of 2024) is 8% per year (adjusted quarterly).
3. Substantial Understatement of Income Tax Penalty (IRC § 6662(a))
If the underpaid tax exceeds 10% of the tax owed or $5,000, the IRS imposes a 20% penalty on the underpayment.
Example:
- IRS disallows a $50,000 deduction, increasing taxable income.
- Additional tax owed = $15,000.
- Penalty = $15,000 × 20% = $3,000.
4. Accuracy-Related Penalty (Negligence or Disregard) – 20% Penalty (IRC § 6662(b))
- If the IRS believes the taxpayer was negligent or failed to maintain proper records, it may impose a 20% penalty on the underpaid tax.
- This is stackable with the substantial understatement penalty, doubling potential penalties.
5. Fraud Penalty – 75% of Underpayment (IRC § 6663)
- If the IRS determines that fraudulent intent was involved, a 75% penalty is imposed on the tax underpayment.
- While rare, fraud penalties can be devastating, leading to IRS investigations and criminal tax liability.
6. Potential for IRS Audits of Prior Years
- If the IRS disallows deductions for one tax year, it may audit prior returns to assess additional back taxes.
- The IRS generally has three years to audit a return, but in cases of substantial understatement (25% or more), the statute of limitations extends to six years.
How to Protect Yourself from IRS Reclassification
To avoid the IRS reclassifying a business as a hobby, taxpayers should:
✅ Maintain Proper Business Records: Keep detailed financial statements, receipts, and a business plan.
✅ Ensure Profit Motive: Show consistent revenue-generating efforts, even if losses occur.
✅ Use Separate Business Accounts: Never mix business and personal finances.
✅ Follow Business Formalities: Register as an LLC or S Corp, and comply with licensing requirements.
✅ Seek Professional Tax Guidance: A CPA or tax attorney can ensure compliance with IRS business criteria.
Final Thoughts
The IRS has the power to retroactively reclassify an activity as a hobby, leading to disallowed deductions, tax reassessments, interest, and penalties. If your business has years of losses, lacks formal business operations, or resembles a personal activity, you may be at risk for IRS scrutiny.
Taxpayers should proactively structure their businesses to meet IRS guidelines
